Apparatus and method for recovery of hydrocarbons from the surface of a body of water

ABSTRACT

An apparatus for the removal of hydrocarbons from a body of water comprising a temperature reduction device comprising a heat exchange in thermal communication with a flow of a liquefied cryogen, the temperature reduction device being adapted to receive a hydrocarbon/water mixture, position a first surface of the at least partially phase separated mixture in thermal communication with the heat exchanger, and reduce the temperature of the at least partially phase separated mixture to a temperature sufficient to cause the hydrocarbon phase to at least partially congeal or at least partially solidify.

TECHNICAL FIELD

The disclosure relates to an apparatus and method of use for removal of hydrocarbon contaminants from water involving cryogenic freezing of the hydrocarbon to facilitate removal.

BACKGROUND ART

U.S. Pat. No. 3,614,873 discloses the general concept of cryogenic freezing of oil on the surface of a body of water. The process described uses a spray of frozen carbon dioxide particles, i.e. dry ice snow, to solidify an oil spill. The solidified oil is then skimmed off the surface of the water using a wire screen. Other Patents describe a similar approach using liquid nitrogen or liquid air as the cryogen. See e.g. U.S. Pat. No. 7,674,373.

To date, these cryogenic techniques have not been adopted by the offshore petroleum production or petroleum transport industries. A limitation of the foregoing techniques relates to the nature of hydrocarbon-water mixtures. In specific respect to oil spills in sea water, the crude oil exists as an emulsion of oil and water having an emulsion zone extending from the surface to a point below the surface. The application of cryogens onto the surface results in inefficient cooling of the majority of the emulsion zone. As the top most portion of the water/oil emulsion solidifies, this initial layer works as a thermal insulating barrier to inhibit freezing the majority of the emulsion zone underneath. As a result, the amounts of crude oil recovered by these prior art processes are less than optimal. Theoretically, these prior art processes could be applied repeatedly to incrementally remove crude oil contamination until a target level of residual oil is reached. The time and expense associated with such an iterative approach renders such an approach impractical. Consequently, there exists an urgent need for an effective device and method for removing hydrocarbons from water such as in the case of oil spills at sea.

DISCLOSURE OF INVENTION

The apparatus has generally two parts, a temperature reduction device and a component for processing and/or storing the recovered hydrocarbons. In preferred embodiments, the apparatus is supported by a floatation platform.

Temperature Reduction Devices

The temperature reduction device generally has the following components:

-   -   A hydrocarbon phase entrance aperture in fluid communication         with a source of hydrocarbon contaminated water, such as crude         oil floating on seawater;     -   A cooling zone having one or both of         -   A heat exchanger in thermal communication with the cooling             zone and configured to reduce the temperature of the             hydrocarbon,         -   One or more cooling fluid delivery nozzles in thermal             communication with the cooling zone and configured to reduce             the temperature of the hydrocarbon,             -   The heat exchanger and fluid delivery nozzles, when both                 present, generally being on opposite sides of the                 hydrocarbon contaminated water in the cooling zone;     -   An at least partially congealed or solidified hydrocarbon phase         exit aperture

In preferred embodiments, the heat exchanger and cooling fluid delivery nozzles cool the hydrocarbon phase in a bidirectional manner e.g. from the top and from the bottom of the hydrocarbon phase. In some bidirectional embodiments, only a partial thickness of the hydrocarbon phase is solidified sufficient to form a sandwich structure capable of containing the central portion of the hydrocarbon layer. Such a partial thickness may 1-2 cm for example.

Recovery/Storage Device

Any suitable means for recovery and storage of the at least partially congealed or solidified hydrocarbon phase may be utilized. The recovery and storage device may be for example any prior device used to recover solidified hydrocarbons from a body of water such as those described in U.S. Patent No. 3,614,873 and 7,674,373, both of which are hereby incorporated by reference for their relevant disclosures of recovery and storage devices. The recovery and storage device may be integral with the rest of the apparatus or a discrete device. In embodiments where the recovery and storage device are discrete, the at least partially congealed or solidified hydrocarbon phase exit aperture is in communication with the body of water having the original hydrocarbon/water mixture. An example of a recovery device is a metal mesh conveyor belt in communication with the at least partially congealed or solidified hydrocarbon phase exit aperture. The temperature reducing device delivers the at least partially congealed or solidified hydrocarbon phase exit to the metal mesh conveyor belt. Any residual water phase from the temperature reducing device may then drain through the mesh while the hydrocarbon layer is retained. The conveyor belt may deliver the hydrocarbons to any suitable container.

Flotation Platform

The apparatus may be installed onto a pre-existing floating platform or adapted with components configured to float the apparatus. Examples of flotation systems suitable for the apparatus are disclosed in U.S. Pat. No. 7,674,373, the relevant contents of which are incorporated by reference. In a preferred embodiment, a floatation platform is capable of supporting and moving an apparatus across the surface of a body of water such as a lake or an ocean. The motive force driving the floatation platform along the surface of the water in such embodiments then serves to move a hydrocarbon/water mixture on the surface of the body of water through the apparatus.

Any suitable means for moving the floatation platform may be utilized. Care should be taken to ensure the devices generating the motive force (e.g. propellers) do not damage the at least partially congealed or solidified hydrocarbon layer if the layer exits the apparatus to return to the surface of the body of water. Alternatively, the floatation platform may be towed behind a ship to provide the motive force.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows a representative schematic of an apparatus falling within the scope of the invention.

FIG. 2 shows a representative schematic of a temperature reduction device falling within the scope of the invention.

SUMMARY OF THE INVENTION

The invention may be understood in relation to the following embodiments:

1. An apparatus for the removal of hydrocarbons from a body of water comprising:

-   -   a) a temperature reduction device (50, 200) comprising a heat         exchanger (240) in thermal communication with a flow of a         liquefied cryogen (250, 260), the temperature reduction device         being adapted to:         -   i) receive a hydrocarbon/water mixture (30, 210),         -   ii) position a first surface of the hydrocarbon/water             mixture in thermal communication with the heat exchanger             (270), and         -   iii) reduce the temperature of the at least partially phase             separated mixture to a temperature sufficient to cause the             hydrocarbon phase (160, 220) to at least partially congeal             or at least partially solidify.             2. The apparatus of sentence 1 further comprising a             hydrocarbon recovery and separation device (70) adapted to:     -   a) receive the least partially congealed or partially solidified         hydrocarbons and the water and/or ice from the temperature         reduction device (60, 280) and     -   b) separate the least partially congealed or partially         solidified hydrocarbons from the water and/or ice.         3. The apparatus of sentence 1 or 2, further comprising a post         heat exchanger cryogen delivery device (290, 310, 320) adapted         to receive the gaseous and/or liquid cryogen from the heat         exchanger (240) of the temperature reduction device (200) and         deliver the cryogen to a second surface (350) of the at least         partially phase separated mixture (220, 230).         4. The cryogen delivery device of sentence 3 wherein the cryogen         delivery device comprises a blower (300) adapted to provide a         motive force to the gaseous and/or liquid cryogen from the heat         exchanger (240).         5. The cryogen delivery device of sentence 3 or 4 further         adapted to receive a supplemental liquid cryogen from a         supplemental liquid cryogen source and deliver the supplemental         liquid cryogen to the surface (350) of the at least         hydrocarbon/water mixture (220, 230).         6. The apparatus of any one of the preceding sentences wherein         the heat exchanger comprises a solid surface heat exchanger         plate (360).         7. The apparatus of any one of the preceding sentences wherein         the cryogen comprises one or more of liquid nitrogen and liquid         carbon dioxide.         8. The apparatus of any one of the preceding sentences wherein         the temperature sufficient to cause the hydrocarbon to at least         partially congeal or at least partially solidify is greater than         zero degrees Celsius such as above 10 degrees Celsius and         preferably from 10 to 25 degrees Celsius.         9. The apparatus of any one of the preceding sentences wherein         the apparatus is adapted to     -   a) float on a body of water and     -   b) receive a mixture of water and hydrocarbon located on the         surface of the body of water.         10. The apparatus of sentence 9 wherein the device is configured         to float as a partially submerged apparatus and the mixture of         water and hydrocarbon is a mixture of sea water and crude oil.         11. The apparatus of any one of the preceding sentences wherein         a hydrocarbon phase has a thickness of 1 to 5 centimeters         12. The apparatus of any of the preceding sentences wherein the         temperature reducing device is adapted to reduce the temperature         of the hydrocarbon/water mixture by the heat exchanger on a         first side and by a flow of gaseous and/or liquid cryogen on a         second side of the hydrocarbon/water mixture.         13. A method of removing hydrocarbons from a hydrocarbon/water         mixture, the method comprising the step of:     -   a) lowering the temperature of the hydrocarbon phase (220) until         at least an outer thickness of less than half of the hydrocarbon         phase (220) is congealed or solidified from a side (350, 370) to         a point within the hydrocarbon phase (220).         14. The method of sentence 14, wherein the temperature of the         hydrocarbon phase (220) is lowered by application of a source of         cooling on a first side (370) and a second side (350) of the         hydrocarbon phase.         15. The method of sentence 14 wherein the cooling of the first         side (370) of the hydrocarbon phase (220) is caused by a heat         exchanger (240) and the cooling of the second side (350) is         caused by a flow of cold gas onto the second side (350).         16. The method of any one of sentences 13-16, wherein the         cooling of the hydrocarbon phase (220) lowers the hydrocarbon         phase (220) temperature to greater than zero degrees Celsius         such as above 10 degrees Celsius and preferably from 10 to 25         degrees Celsius,

MODE(S) FOR CARRYING OUT THE INVENTION

FIG. 1 shows a generalized schematic of an embodiment of the apparatus and process described herein. The hydrocarbon/water mixture 10 above water 20 enters through aperture 30 into the temperature reducing unit 50. Temperature reducing unit 50 cools the hydrocarbon to form an at least partially solidified hydrocarbon layer. This at least partially solidified hydrocarbon is then moved out of the temperature reducing unit 50 through aperture 60 and into a collection unit 70. The collection unit may be integral or separate from the temperature reducing unit 50.

FIG. 2 shows an example temperature reducing device. In this example, the hydrocarbon is crude petroleum. The crude petroleum phase layer 220 enters through aperture 210. In general for the apparatus of the invention, the hydrocarbon layer will enter the temperature reducing device as a layer floating on a small water layer 230 (the water layer preferably being no more than 3 cm thick). Heat exchanger 240 is located beneath the water layer 230. A source of cryogenic fluid 250 feeds liquid cryogen under pressure through nozzles 260 to chill the heat exchanger surface 270. The hydrocarbon phase congeals or solidifies as it passes through the cooling zone 340. The solidified pr congealed hydrocarbon phase then exists through aperture 280.

The liquid cryogen in the heat exchanger vaporizes over time to form a cold gas. This cold gas is transported through pipe 290 into an overhead chamber 310. Optionally a blower 300 is in fluid communication with the pipe 290 to pressurize the cold gas more than the intrinsic pressure derived from the vaporization in the heat exchanger. Overhead chamber 310 is in fluid communication with a plurality of nozzles 320. The cold gas flushes through nozzles 320 and onto the surface 350 of the crude petroleum phase layer 220. Optionally, the cold gas is chilled by a refrigeration system and/or augmented with a liquid cryogen to enhance the cooling speed and/or depth penetration of the cooling from the crude petroleum phase layer surface 350.

A portion of the vaporized cryogen does not pass through the nozzles 320 but exits through vent line 330.

INDUSTRIAL APPLICABILITY

The present invention is at least industrially applicable to the removal of petroleum contamination from an area of sea water.

It will be understood that many additional changes in the details, materials, steps and arrangement of parts, which have been herein described in order to explain the nature of the invention, may be made by those skilled in the art within the principle and scope of the invention as expressed in the appended claims. Thus, the present invention is not intended to be limited to the specific embodiments in the examples given above. 

1. An apparatus for the removal of hydrocarbons from a body of water comprising: a) a temperature reduction device comprising a heat exchange in thermal communication with a flow of a liquefied cryogen, the temperature reduction device being adapted to: i) receive a hydrocarbon/water mixture, ii) position a first surface of the at least partially phase separated mixture in thermal communication with the heat exchanger, and iii) reduce the temperature of the at least partially phase separated mixture to a temperature sufficient to cause the hydrocarbon phase to at least partially congeal or at least partially solidify.
 2. The apparatus of claim 1, further comprising a hydrocarbon recovery and separation device adapted to: a) receive the least partially congealed or partially solidified hydrocarbons and the water and/or ice from the temperature reduction device and b) separate the least partially congealed or partially solidified hydrocarbons from the water and/or ice.
 3. The apparatus of claim 1, further comprising a post heat exchanger cryogen delivery device adapted to receive the gaseous and/or liquid cryogen from the heat exchanger of the temperature reduction device and deliver the cryogen to a second surface of the at least partially phase separated mixture.
 4. The cryogen delivery device of claim 3, wherein the cryogen delivery device comprises a blower adapted to provide a motive force to the gaseous and/or liquid cryogen from the heat exchanger.
 5. The cryogen delivery device of claim 3, further adapted to receive a supplemental liquid cryogen from a supplemental liquid cryogen source and deliver the supplemental liquid cryogen to the surface of the hydrocarbon/water mixture.
 6. The apparatus of claim 3, wherein the heat exchanger comprises a solid surface heat exchanger plate.
 7. The apparatus of claim 3, wherein the cryogen comprises one or more of liquid nitrogen and liquid carbon dioxide.
 8. The apparatus of claim 3, wherein the temperature sufficient to cause the hydrocarbon to at least partially congeal or at least partially solidify is greater than zero degrees Celsius.
 9. The apparatus of claim 3, wherein the apparatus is adapted to a) float on a body of water and b) receive a mixture of water and hydrocarbon located on the surface of the body of water.
 10. The apparatus of claim 9, wherein the device is configured to float as a partially submerged apparatus and the mixture of water and hydrocarbon is a mixture of sea water and crude oil.
 11. The apparatus of claim 3, wherein a hydrocarbon phase of the hydrocarbon/water mixture has a thickness of 1 to 5 centimeters.
 12. The apparatus of claim 3, wherein the temperature reducing device is adapted to reduce the temperature of the hydrocarbon/water mixture by the heat exchanger on a first side and by a flow of gaseous and/or liquid cryogen on a second side of the hydrocarbon/water mixture.
 13. A method of removing hydrocarbons from a hydrocarbon/water mixture, the method comprising the step of: a) lowering the temperature of the hydrocarbon phase until at least an outer thickness of less than half of the hydrocarbon phase is congealed or solidified from a side to a point within the hydrocarbon phase.
 14. The method of claim 13, wherein the temperature of the hydrocarbon phase is lowered by application of a source of cooling on a first side and a second side of the hydrocarbon phase.
 15. The method of claim 14, wherein the cooling of the first side of the hydrocarbon phase is caused by a heat exchanger (240) and the cooling of the second side are caused by a flow of cold gas onto the second side.
 16. The method of claim 13, wherein the cooling of the hydrocarbon phase lowers the hydrocarbon phase temperature to greater than zero degrees Celsius. 